The articles and essays in this blog range from the short to the long. Many of the posts are also introductory (i.e., educational) in nature; though, even when introductory, they still include additional commentary. Older material (dating back mainly to 2005) is being added to this blog over time.

Friday, 27 March 2015

Ernan McMullin: Are Scientific Theories True?

Karl
Popper once said that the notion of truth is counter-productive in
science because it brings the/a scientific story to an end.
Instead Popper talked about verisimilitude. However, many
would argue that the notion of truth is actually contained in the
notion of verisimilitude. In fact Ernan McMullin (in his 'A
Case for Scientific Realism') makes that point point when he
writes that the

“term
'approximate truth'.... is risky because it immediately invites
questions such as: how approximate, and how is the degree of
approximation to be measured?”

Yes,
truth is hiding in the background here. Not only that: in order to
know that a theory is approximately true, wouldn't one also need to know
what would make it completely true and what makes it partly false?
And in order to know that, wouldn't one also need to know what the
complete truth of that theory is? Therefore, on this reading, there
would be no approximation or verisimilitude about it. In any case,
Ernan McMullin puts the same – or a similar – point. He writes:

“I
do not think that acceptance of a scientific theory involves the
belief that it is true. Science aims at fruitful metaphor and at ever
more detailed structure. To suppose that a theory is literally true
would imply, among other things, that no further anomaly could, in
principle, arise from any quarter in regard to it.”

Strictly
speaking, only statements and propositions can be true or false.
Nonetheless, if a theory is seen as a simple collection of true
statements, then it can be seen as true if all the statements it
contains are also true.

Yet
scientific theories don't work like that.

Even
though theories do contain statements, not all those statements can
be seen as being either true or false. Some involve predictions,
probabilities, conjectures and whatnot. Only few of the statements or
expressions which make up a theory have an entirely truth-conditional
content.

If
we bear in mind the McMullin quote above, it's also clear that a
“fruitful metaphors” can't be true either.

What
McMullin also seems to be arguing is that a “worldly structure”
shows itself only slowly – over time. Each successive theory about
the (same?) structure comes closer to the truth. However, since this
is ongoing process concerning theories about structure x, then no
single theory of x can ever be said to be conclusively true.

McMullin gives an example of this. He says that

“[s]cientists
in general accept the quantum theory of radiation. Do they believe it
to be true? Scientists are very uncomfortable at this use of the word
'true' because it suggests that the theory is definitive in its
formulation”.

In
other words, scientists don't need to classify their theories as
true. Indeed it can even be said that scientists don't need truth at
all. Instead a scientist can “accept an explanation as the best
available”. Moreover, “one accepts a theory as a good basis for
further research”.